Air Quality Terminology

June 21, 2012

Most of us know that the air quality inside our homes can be of much lower quality than the air outside our homes, and want to know how we can improve it; but what do all those technical terms mean? Here are some simple-to-understand definitions of common terms.

  • Air Cleaning: A way to remove various airborne particulates and/or gases from the air.
  • Air Exchange Rate: The rate at which outside air is exchanged with indoor air.
  • Air Handling Unit (AHU): Equipment including a blower or fan, heating and/or cooling coils, and all other related equipment such as air filters and drain pans.
  • Animal Dander: Tiny pieces of animal skin.
  • Allergen: Any substance that is capable of causing allergic reactions in persons with sensitivities to that substance.
  • Antimicrobial: Kills microbial growth.
  • Air Pollutant: Any foreign or natural substance that can harm humans, animals, plants, or materials.
  • Air Pollution: Unwanted chemicals or other materials in the air that causes air quality to decline.
  • Air Quality Index (AQI): A measure of the severity of air pollution. Ranges from 0 (good) to 500 (hazardous). Includes levels of ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
  • Asthma: Chronic disorder of the lungs that includes inflammation, wheezing, chest tightness, shortness of breath, and cough.
  • Biological Contaminants: Air contaminants from living organisms including viruses, bacteria, fungi, and dander. When inhaled, biological contaminants can cause allergic reactions, aggravate respiratory disorders, or transmit disease.
  • Carbon Monoxide (CO): Colorless, odorless gas created by the incomplete combustion of fuel.  Interferes with body’s ability to carry oxygen to tissues. 
  • Chlorofluorocarbons (CFCs): Used for refrigeration and air conditioning, solvents, and propellants. Consist of chlorine, fluorine, and carbon.
  • Criteria Air Pollutant: Any air pollutant which has an acceptable level of exposure.  Includes carbon monoxide, ozone, sulfur dioxide, and nitrogen dioxide.
  • EPA: U.S. Environmental Protection Agency, responsible for regulation of pesticides, toxic chemicals, hazardous wastes, and toxic pollutants in water and air.
  • Fume: Solid particles that are less than 1 micron in diameter, formed by condensing vapors or chemical reactions.
  • Gaseous pollutants: Pollutants produced during combustion, such as in cooking stoves, vehicle exhaust, and tobacco smoke.
  • HEPA: Acronym for High Efficiency Particulate Arresting filters.
  • Indoor Air Pollutant: Any substance that lowers indoor air quality, including particles, dust, fibers, gases or vapors.
  • Mechanical air filters: Filters located within a heating and cooling system to remove particles by capturing them on filter materials.
  • Natural Ventilation: Air movement into and out of a home through holes, cracks, and open windows and doors.
  • Particulate matter: Particles in the air,  including dust, smoke, pollen, animal dander, tobacco smoke, fumes, gasses, dust mites, molds, bacteria, and viruses.
  • Sanitizer: A mechanical air cleaner that greatly reduces the microorganisms in the air.
  • Sterilizer: A mechanical air cleaner that destroys or eliminates all forms of bacteria, fungi, viruses, and their spores, which are considered the most difficult form of a microorganism to destroy.
  • UVGI cleaners: Use ultraviolet radiation from UV lamps to destroy biological pollutants such as viruses, bacteria, allergens, and molds that are airborne or growing on heating and cooling surfaces.



Last Updated: June 09, 2023